Position indicator for elongatable actuators such as hydraulic cylinders



Feb. 12, 1963 E. EVANSON 3,077,179

POSITION INDICATOR FOR ELONGATABLE ACTUATORS SUCH AS HYDRAULIC CYLINDERS Filed Aug. 22, 1961 I INVENTOR ImlZZ'Vammn ATTORNEY? 3,977,179 Patented Feb. 12, 1963 hoe 3,077,179 PGSHTION INDICATGR FQR ELUNGATABLE ACTUATGIRS SUCH AS HYDRAUHC CYL- INDERS Emil Evanson, Forman, N. Dali. Filed Aug. 22, 1961, Ser. No. 133,229 3 Claims. (Cl. 116 124) This invention relates generally to position indicators for use with elongatable power actuators. More specifically, it is directed to an indicator device mountable in association with an axially elongatable power actuator, for example, actuators as commonly referred to as hydraulic cylinders, to be effective to indicate the relative degree of extension and retraction in length of the actuator.

For purposes of description herein, reference will be made to a conventional hydraulic cylinder with which the indicator device of the invention may be employed. The hydraulic cylinder type of actuator in its conventionally recognized form embodies a cylinder having a bore within which a piston is reciprocably mounted with the piston having a rod extending axially outwardly through an end of the cylinder. The hydraulic cylinder is operated to extend or retract the piston rod by the introduction of hydraulic fluid into one or the other ends of the cylinder to act on a face of the piston in extending or retracting the piston rod. Although this specific form of elongatable power actuator is illustrated and described hereinafter in connection with the manner in which the indicator device of the invention is employed and functions, it is to be understood that the term elongated power actuator contemplates not only the hydraulic cylinder type specifically illustrated, but also air cylinder actuators, screw and nut elongatable actuators and in general, all elongatable actuators having members which are relatively axially movable in extension and retraction operations of the actuator.

In effecting the actuation of machinery components, extensive use has been made of elongatable power actuators. Such actuators provide a convenient means Whereby a machine element or part may be moved from one position to another under control of the machinery operator at a remote point from the particular element being actuated. One example of the use of such elongatable actuators arises in connection with farm machinery. Be cause of the ease of control and of obtaining the transmission of substantial operating force, extensive use of hydraulic systems has been made in connection with tractor-drawn farm machinery. By means of such systems, control of the positioning of particular elements of the machinery may be readily effected from the tractor by appropriate valving mounted adjacent the tractor seat and the hydraulic fluid conducted to the machinery element whereat hydraulic cylinders are mounted to apply the operating force for operation of the machine element under control of the valving manipulated by the tractor operator.

A specific instance Where elongatable actuators of the hydraulic cylinder type come into use is in connection with the operation of tractor-drawn plows. The raising and lowering of the plow is now quite frequently effected by the use of a hydraulic cylinder with control of the extension and retraction of the cylinder being atfected by the operator from his station on the tractor, this control being carried out by opening and closing valves to admit to or Withdraw from the hydraulic cylinder the desired amount of fluid which produces a corresponding movement of the piston rod of the hydraulic cylinder. The fluid is trapped in the cylinder to hold the plow in the selected position.

Where the machinery and machine element thereof to be operated permits the elongatable actuator to be mounted in a position such that the operator may visually observe th degree of extension or retraction of the actuator, it is not particularly difiicult for the operator to adjust the actuator to affect appropriate location of the machine element which is operated by the actuator. Even in this situation, if the particular position of the machine element being operated is critical in connection with overall functioning of the machinery, it may be difficult for the operator to accurately judge by mere visual approximation the extended length of the actuator and as to whether the machine element is properly positioned.

Where the actuator is mounted on the machinery, as quite frequently is required in positioning the hydraulic cylinder which controls tractor-drawn farm implements, so that the aXis of elongation of the actuator is generally aligned with the line of sight of the operator, it is quite difiicult for the operator to accurately judge in each instance the degree to which the actuator is elongated in positioning the particular element on the machinery which is being operated. This gives rise to the need for an indicator which may be appropriately associated with the elongatable actuator and provide a visual indication to the equipment operator of the degree to which the length of the actuator is extended. With such a position indicator, the operator may accurately locate the machinery element in each instance to insure that such element will be properly positioned by reason of the actuator being extended or retracted to a particular overall length.

It is a principal object of the instant invention to provide an indicator device mountable in association with an axially elongatable power actuator and being of improved, simple and rugged construction whereby the relative degree of extension or retraction of the actuator may be visually discerned by an operator disposed remote from the actuator.

A further object of the instant invention is to provide an indicator device useabl with axially elongatable power actuators which is of rugged construction such as to be reliably operable for long periods of use even when exposed to dirt and dust or other adverse operating cond-itions.

It is also an object of the instant invention to provide a position indicator for power actuators particularly of the hydraulic cylinder type wherein a scale carrying dial is mounted to be transversed by a pointer, which pointer is positively driven by a helical thread oi relatively long pitch formed on a rod of irregular cross-section with the rod engaging a bore of corresponding irregular crosssection to move the pointer in direct relation to extension and retraction of the actuator.

The above and other objects of the instant invention will be apparent from the following description taken in connection with the accompanying drawing. It is to be expressly understood that the drawing is for the purpose of illustration only and is not intended to define the limits of the invention, but rather to merely illustrate a preferred embodiment and structure incorporating the features of the instant invention.

In the drawing wherein like reference numerals are employed to designate like parts throughout the several views:

FIGURE 1 is a side elevational view showing the indicator device of the instant invention mounted in association with an axially elongatable power actuator of the hydraulic cylinder type;

FIGURE 2 is an end elevational view taken from the right end of the structure shown on FIGURE 1; and

FIGURE 3 is an enlarged sectional view taken .on line 3-3 of FIGURE 2 showing details of the construction of the indicator device.

The indicator device is shown on the drawing mounted tended -to one-half its stroke.

in association with an elongatable actuator of the hydraulic cylinder type designated generally by the reference character 10. This actuator which is merely representative of elongatable actuators with which the instant invention may be employed includes a cylinder 11 which has a piston reciprocably mounted therein with a piston rod 12 connected to the piston and extending outwardly through one end of cylinder 11. The outer end of rod 12 may be provided with a suitable clevis 13 while the opposite end of cylinder 11 is shown with a clevis 14.

As is well recognized in utilization of elongatable actuators such as designated at 10, the actuator will be mounted by means of clevises 13 and 14 by connecting them respectively to a stationary point on the machinery and to the machine element to be operated by extension and retraction of the actuator. Appropriate connections (not shown) for introducing hydraulic fluid into one or the other ends of the cylinder 11 are provided to affect the extension or retraction of rod 12 in accordance with the operation desired for the machine element controlled by the actuator.

It is deemed unnecessary to illustrate a particular machine elernent to be operated by the actuator since an infinite number of machinery applications may be made for actuators and the particular machine element operated forms no part of the instant invention. This invention as outlined above, is directed to the position indicator for the actuator by means of which the machine operator may observe the degree to which the actuator is extended or retracted. As will be apparent from the description below, the indicator device of the instant invention is particularly advantageous where the machinery operators view of the actuator is such that he views the longitudinal extent of the actuator and thus encounters extreme difiiculty in discerning the position of the actuator and the element operated by means of the actuator.

The indicator device includes a plate 20 which forms a dial 21 having a scale indicia 22 arrayed on one face thereof. The indicia 22 indicated on FIGURE 2 as embracing the number series 1 through 8 may be appropriately disposed on dial 21 to indicate either arbitrarily or specifically the extended condition of the actuator. For example, the dial 21 shown on FIGURE 2 might be employed for a standard eight-inch stroke hydraulic cylinder. In .this case, the indicia 1 through 8 would indicate the number of inches to which the piston rod of the cylinder has been extended or retracted. Thus, with the indicating device registering at 4, the operator would be immediately apprised of the fact that the cylinder is ex- Alternatively, the indicia on the scale may represent an arbitrary member, letter, etc., series to indicate the relative extent of elongation of the actuator.

The plate 29 is mounted on the end of cylinder 11 as by means of suitable screws 23. It will be appreciated that any appropriate means may be employed to afiix the plate 20 on the cylinder 11 in place of the screw fastening means. To facilitate the oper-ators visually observing the indicator device when the actuator is disposed to extend longitudinally away from the operator, it is desired that .the plate 20 be mounted so as to lie in a plane generally normal to the longitudinal axis of the actuator, in the illustrated embodiment normal to the axis of cylinder 11.

Referring to FIGURE 3, it will be noted that the plate 20 .is provided with a-bore 25 which is disposed at the 'center of the dial 21 carrying the indicia 22 which in dicia are shown in FIGURE 2 as being spaced around the circumference of the dial 21. A bearing unit 26 is retatably mounted in bore 25 and includes a washer 27 which is rotatable with the unit relative to the plate 20.

A pointer 3h is secured to the outer face of washer 27 on unit 26, this pointer extending radially outwardly to traverse the scale indicia 22 in operation of the indicator device. The pointer 30 mounts a drive element at its inner end defining a square bore 31 at the center of rotation of the pointer 30. The bearing unit 26 has a bore 32 aligned with the square bore 31. Although the drive element defining square bore 31 is shown as being integral with the pointer 35% it will be readily appreciated that the pointer and drive element may be separate and also that the drive element may be coupled to swing the pointer other than by being fixedly secured thereto.

The drive element providing the square bore 31 is en gaged with a spiral rod 35, the rod being shown as hav ing a square cross-section throughout its length. The square rod 35 is twisted throughout its length to form the spiral which in turn provides along the length of the rod a helical thread of relatively long pitch. As shown in FIGURE 1, rod 35 has one end fixedly mounted in a holder 36 which is carried by a bracket 37 connected to clevis 13.

The spiral rod 35 forms a helical thread and the crosssection of the rod which corresponds to the cross-section of bore 31 in pointer 38'cooperates with the pointer such that as the rod moves through the bore 31, the helical thread on the rod will causes the pointer 30 to turn in accordance with the pitch of the thread.

The operation of the indicator device will be readily appreciated from the structural description hereinabove. The spiral rod 35 carried by the outer end of piston rod 12 will be moved from the solid line position shown in FIGURE 1 to the position shown in phantom on FIG- URE 1 as the piston rod is retracted. The square spiral rod 35 being fixedly secured in holder 36 will, by its engagement with the square bore 31 in pointer 30, cause the pointer to swing across the dial 21 on plate 30 traversing the scale indicia 22 thereon as the piston rod 12 is retracted. Likewise, when the piston rod 12 is extended, the square spiral rod 35 will be Withdrawn through the square bore 31 of pointer B ll and cause the pointer to swing back across the scale indicia 22. Thus, for any specific degree of elongation of the actuator, the position of pointer 30 on dial 21 will reflect to the machinery operator the state of the actuators elongation.

Although, as specifically illustrated, the rod 35 has been indicated as having a square cross-section to cooperate with the square bore 31 in pointer 30, it will be appreciated that any suitable irregular cross-section for the rod and corresponding cross-section for the bore may be employed to obtain the operation required for actuation of the pointer by movement of the rod through the bore formed in the pointer. Thus the rod and bore may have a corresponding triangular, rectangular or other polygonal cross-sectional.

It is further contemplated that, Within the scope of the instant invention, the plate 2% may be carried out at the outer end of the piston rod 12 and the holder 36 and spiral rod 35 mounted on the cylinder 11. Additionally, to achieve the desired movement of the pointer across dial 21 as the actuator elongates or shortens, the spirally formed rod 35 may be fixedly mounted to the pointer which is rotatable relative to the dial with the dial secured to one member of the elongatable power actuator. In such a construction, the irregular cross-section of the spiral rod will slidably engage with a correspondingly formed irregular cross-section bore with such oore being formed in means which are fixedly secured to the other member of the elongatable power actuator.

To further facilitate visually determining the position of pointer 34 relative to scale indicia 22 the dial may be provided, if desired, with suitable means for illuminating the scale indicia on the dial.

'It is to be understood that the form of this invention herewith shown and described is to be taken as a preferred example of the same and that in addition to the hereinabove mentioned modifications, various changes in shape, size and arrangement of the parts maybe resorted to without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. An indicator device for use with an elongatable power actuator having cylinder member and a piston rod member extensible from said cylinder member upon introduction of fluid pressure into the cylinder member comprising a dial provided with means for mounting it relative to the one of the actuator members to be disposed in a plane generally normal to the elongation axis of the actuator, said dial having scale indicia thereon to indicate the relative degree of extension of the cylinder and piston rod members relative to each other, a pointer mounted relative to said dial to be swingable through an arc encompassing said scale indicia, operating means for said pointer including a spiral rod element to be mounted parallel to the elongation axis of the actuator with said rod element having an irregular cross-section, said spiral forming a helical thread of long pitch along the length will cause relative rotative movement between said ele-' ments, means for fixedly mounting one of said elements on the other of the actuator members, and the other of said elements being fixedly secured to said pointer to swing it and traverse the scale indicia to indicate the position of the cylinder and piston rod members with respect to each other.

2. An indicator device for association with an elongatable actuator having a cylinder and piston rod extensible from such cylinder upon introduction of fluid pressure into the cylinder comprising a dial provided with means for mounting it relative to the cylinder of the actuator to be disposed in a plane generally normal to the elongation axis of the actuator, said dial having scale indicia thereon to indicate the relative degree of extension of the cylinder and piston rod relative to each other, a pointer mounted relative to said dial to be swingable through an arc encompassing said scale indicia, operating means for said pointer including a spiral rod element having an irregular cross-section, means for fixedly mounting said rod element parallel with the piston rod to move therewith, said spiral forming a helical thread of long pitch along the length of the rod element, said pointer mounting means providing a drive element movable with said pointer, said drive element defining an aperture having a cross-section corresponding to the cross-section of said rod element, said rod element slidably engaging through said drive element whereby movement of said drive element along said rod element will cause rotative movement of the pointer to swing it and traverse the scale indicia to indicate the position of the cylinder and piston rod with respect to each other.

3. The combination of an elongatable actuator having a cylinder and piston rod extensible from such cylinder upon introduction of fluid pressure into the cylinder, a dial fixedly mounted on said cylinder to be disposed in a plane generally normal to the elongation axis of the actuator, said dial having scale indicia thereon to indicate the relative degree of extension of said cylinder and piston rod relative to each other, a pointer mounted relative to said dial to be swingable through an arc encompassing said scale indicia, operating means for said pointer including a spiral rod element having an irregular cross-section with said rod element being fixedly mounted on and parallel to said piston rod, said spiral forming a helical thread of long pitch along the length of the rod element, said pointer mounting means thereon providing a drive element movable with said pointer, said drive element defining an aperture having a cross-section corresponding to the crosssection of said rod element, said rod element slidably engaging through said drive element whereby movement of said drive element along said rod element will cause rotative movement of the pointer to swing it and traverse the scale indicia to indicate the position of said cylinder and piston rod with respect to each other.

Taylor Feb. 4, 1930 Luskenko Mar. 15, 1955 

1. AN INDICATOR DEVICE FOR USE WITH AN ELONGATABLE POWER ACTUATOR HAVING CYLINDER MEMBER AND A PISTON ROD MEMBER EXTENSIBLE FROM SAID CYLINDER MEMBER UPON INTRODUCTION OF FLUID PRESSURE INTO THE CYLINDER MEMBER COMPRISING A DIAL PROVIDED WITH MEANS FOR MOUNTING IT RELATIVE TO THE ONE OF THE ACTUATOR MEMBERS TO BE DISPOSED IN A PLANE GENERALLY NORMAL TO THE ELONGATION AXIS OF THE ACTUATOR, SAID DIAL HAVING SCALE INDICIA THEREON TO INDICATE THE RELATIVE DEGREE OF EXTENSION OF THE CYLINDER AND PISTON ROD MEMBERS RELATIVE TO EACH OTHER, A POINTER MOUNTED RELATIVE TO SAID DIAL TO BE SWINGABLE THROUGH AN ARC ENCOMPASSING SAID SCALE INDICIA, OPERATING MEANS FOR SAID POINTER INCLUDING A SPIRAL ROD ELEMENT TO BE MOUNTED PARALLEL TO THE ELONGATION AXIS OF THE ACTUATOR WITH SAID ROD ELEMENT HAVING AN IRREGULAR CROSS-SECTION, SAID SPIRAL FORMING A HELICAL THREAD OF LONG PITCH ALONG THE LENGTH OF THE ROD ELEMENT, AND A COOPERATING DRIVE ELEMENT PROVIDED WITH AN APERTURE HAVING A CROSS-SECTION CORRESPONDING TO THE CROSS-SECTION OF SAID ROD ELEMENT, SAID ROD ELEMENT SLIDABLY ENGAGING THROUGH SAID APERTURE WHEREBY MOVEMENT OF SAID DRIVE ELEMENT ALONG SAID ROD ELEMENT WILL CAUSE RELATIVE ROTATIVE MOVEMENT BETWEEN SAID ELEMENTS, MEANS FOR FIXEDLY MOUNTING ONE OF SAID ELEMENTS ON THE OTHER OF THE ACTUATOR MEMBERS, AND THE OTHER OF SAID ELEMENTS BEING FIXEDLY SECURED TO SAID POINTER TO SWING IT AND TRAVERSE THE SCALE INDICIA TO INDICATE THE POSITION OF THE CYLINDER AND PISTON ROD MEMBERS WITH RESPECT TO EACH OTHER. 